Patterning method using thiosulfate polymer and metal nanoparticles

ABSTRACT

A thiosulfate polymer composition includes an electron-accepting photosensitizer component, either as a separate compound or as an attachment to the thiosulfate polymer. The thiosulfate polymer composition can be used in methods to form predetermined patterns of metal nanoparticles.

CROSS-REFERENCE TO RELATED APPLICATIONS

This is a Continuation-in-part of U.S. Ser. No. 13/847,083 filed Mar.19, 2013, which is incorporated herein by reference in its entirety.

U.S. Ser. No. 14/158,883, filed on Jan. 20 2014 by Shukla, Mis, andMeyer, which is a Continuation-in-part application of U.S. Ser. No.13/846,985, filed on Mar. 19, 2013.

U.S. Ser. No. 14/158,884, filed on Jan. 20, 2014 by Shukla, Donovan, andMis, which is a Continuation-in-part application of U.S. Ser. No.13/847,031, filed on Mar. 19, 2013.

U.S. Ser. No. 14/158,890 filed on Jan. 20. 2014 by Shukla and Donovan,which is a Continuation-in-part application of U.S. Ser. No. 13/847,049,filed on Mar. 19, 2013.

U.S. Ser. No. 14/158,897, filed on Jan. 20, 2014 by Mis and Shukla,which is a Continuation-in-part application of U.S. Ser. No. 13/847,063,filed on Mar. 19, 2013.

FIELD OF THE INVENTION

This invention relates to a method for forming patterns usingcompositions comprising photosensistive thiosulfate polymers.

BACKGROUND OF THE INVENTION

Alkylthiosulfates (R—S—SO₃ ⁻Na⁺), known as Bunte salts, have been knownfor a long time [Bunte, H. Chem. Ber. 1874, 7, 646]. These salts arereadily prepared by reacting alkylhalides with sodium thiosulfate.Extensive reviews on the preparation and classical reactions of Buntesalts have appeared in the literature (for example, Milligan, B.; Swan,J. M. Rev. Pure Appi. Chem. 1962, 12, 72).

Much of the useful chemistry of Bunte salts results from the potentialof the sulfite moiety to leave the molecule. Small molecule Bunte saltshave various uses. For instance they can be used as insecticides orfungicides, radiation protecting agents (for example as described inU.S. Pat. No. 5,427,868 of Bringley et al.), and paint additives.

Polymeric Bunte salts and Bunte salt derivatives have been used forsetting hair as described in U.S. Pat. No. 5,071,641 (Lewis) and U.S.Pat. No. 5,424,062 (Schwan et al.).

Water-soluble polymers formed from thiosulfate salts are useful in avariety of applications including their use to crosslink or otherwisemodify the properties of natural materials such as wool fibers,cellulosic fibers, and leathers, and as water-insoluble polymeric sulfurdyes. These water-soluble polymers are also used in the coatingindustry.

Bunte salts are commonly reduced to corresponding thiols either bydecomposition with mineral acids or by treatment with reducing agentssuch as NaBH₄, dithioerythritol, or mercaptoethanol. In addition, Buntesalts can be decomposed to disulfides at moderate temperatures. In solidstate, Bunte salts are known to decompose upon heating to formdisulfides, a feature that has been used as thermally switchable imagingmaterials in printing plates. By “switchable” is meant that the polymeris rendered from hydrophilic to relatively more hydrophobic, or fromhydrophilic to relatively more hydrophobic, upon exposure to heat. Forexample, U.S. Pat. No. 5,985,514 (Zheng et al.) and U.S. Pat. No.6,465,152 (DoMinh et al.) describe lithographic printing plateprecursors that are composed of thiosulfate containing polymers, whichupon exposure to IR radiation are crosslink as the thiosulfate groupsare decomposed.

Bunte salts can be used to synthesize disulfides by oxidation [Affleck,J. G.; Dougherty, G. J. Org. Chem. 1950, 15, 865. and Milligan, B. L.;Swan, L. M. J. Chem. Soc. 1962, 2172], acidic hydrolysis [Kice, J. L. J.Org. Chem. 1963, 28, 957], or alkaline degradation [Alonso, M. E.;Aragon, H. Org. Synth. 1978, 58, 147]. Disulfides also can be formedfrom Bunte salts electrochemically [Czerwinski, A.; Orzeszko, A.;Kazimierczuk, Z.; Marassi, R.; Zamponi, S. Anal. Lett. 1997, 30, 2391].This method has been extended to form polydisulfides from “double” Buntesalts, that is, molecules carrying two thiosulfate groups, usingelectrochemistry with gold electrodes [Nann, T.; Urban, G. A. J.Electroanal. Chem. 2001, 505, 125].

In all these noted methods, the Bunte salts are either decomposed byheating or electrochemically in solution, or at high pH. No efficientphotochemical method to decompose Bunte salts is known. Morespecifically, a simple method for patterning thin films using Bunte saltpolymers is not known and would be desirable for various purposes.

It would be very desirable to decompose thiosulfate polymers byphotochemical means, or by using a photochemical electron transferprocess (also known as photoinduced electron transfer).

SUMMARY OF THE INVENTION

This invention provides a method, comprising:

-   -   providing a polymeric layer comprising a non-crosslinked        thiosulfate polymer that also comprises pendant organic charged        groups,

photochemically reacting the non-crosslinked thiosulfate polymer toprovide polymeric layer areas comprising a crosslinked polymer havingdisulfide groups in the polymeric layer,

-   -   optionally washing the polymeric layer to remove any        non-crosslinked thiosulfate polymer while leaving the        crosslinked polymer having disulfide groups in the polymeric        layer, and    -   contacting the polymeric layer with a dispersion of metal        nanoparticles to complex the metal nanoparticles with the        crosslinked polymer having disulfide groups.

In another embodiment of this invention, a method of forming a patternin a polymeric composition, comprises:

-   -   providing a polymeric layer or a nonpolymeric layer comprising        an electron-accepting photosensitizer component,    -   providing a polymeric layer comprising a non-crosslinked        thiosulfate polymer adjacent to the polymeric layer or        nonpolymeric layer comprising the electron-accepting        photosensitizer component,    -   photochemically reacting the non-crosslinked thiosulfate polymer        to provide a crosslinked polymer having disulfide groups in a        predetermined pattern in the polymeric layer, leaving        non-crosslinked thiosulfate polymer in area(s) outside of the        predetermined pattern,    -   optionally washing the polymeric layer to remove the        non-crosslinked thiosulfate polymer while leaving the        crosslinked polymer having disulfide groups in the predetermined        pattern, and

treating the crosslinked polymer having disulfide groups with adisulfide-reactive material.

The present invention can be used to provide patterns by decomposingpolymeric Bunte salts using a photochemical electron transfer (alsocalled photoinduced electron transfer) process. In addition, the presentinvention can be used to provide negative working photoresistscomprising a Bunte salt polymer and a photoactivated electron acceptor,and the surface energy of the photoresist can be modified. Other methodsof the present invention can be used to obtain conductive ornon-conductive metal coatings after photochemical reaction of thethiosulfate polymers.

Many advantages of this invention are achieved using polymeric Buntesalts in the presence of electron-accepting photosensitizer components.In some embodiments, the electron-accepting photosensitizer componentsare separate compounds used in mixture with the thiosulfate polymers,while in other embodiments, the electron-accepting photosensitizercomponents are covalently attached to the thiosulfate polymers. Theelectron-accepting photosensitizer components can be selected to providesensitivity to any desired spectral absorption.

Most compositions used in this invention are light sensitive and canprovide light sensitive imaging layers, which when exposed to actinicradiation (generally less than 750 nm) the exposed regions are renderedinsoluble, thereby providing a pattern that can be used for a variety ofpurposes such as surface energy modulation or electroless metal plating.

The present invention provides at least the following advantages:

1. This invention involves a photo-initiated electron transfer reactionin a solid thiosulfate polymer that creates changes in the solubility ofthe material. Because the invention relies on photo-initiated electrontransfer rather than thermal decomposition, resolution of resultingpatterns is much greater.

2. The thiosulfate polymer composition uses a stable thiosulfate polymerthat can be conveniently fabricated into films, slabs, discs, and othersolid forms. In addition, the thiosulfate polymers can be incorporatedinto porous or non-porous polymeric particles and such particles can beprovided and used as dispersions or emulsions, or provided as coatings.

3. The solubility changes in the thiosulfate polymer composition arelarge, permanent, localized, and can easily be detected, forming thebasis for patterning.

4. In some embodiments, covalent attachment of the electron-acceptingphotosensitizer component to a thiosulfate polymer backbone (as opposedto simply dissolving the component in the thiosulfate polymer to form asolid solution) allows for the incorporation of much higher effectiveconcentration of such electron-accepting photosensitizer componentswithout problems associated with phase separation such ascrystallization. Higher concentrations of the electron-acceptingphotosensitizer component lead to desirable increases in changes inphotochemical sensitivity, thereby improving the performance of thethiosulfate polymer composition and resulting coatings. In addition, thepermanence of recorded information in the resulting patterns is improveddue to low mobility of high molecular weight structures.

5. Coatings of the thiosulfate compositions can be used to modulatesurface characteristics such as changing part (pattern) or all of asurface from a hydrophilic nature to a hydrophobic nature.

One purpose of the present invention is to provide a photosensitiveresin composition, which after exposure to light, undergoes a reactionthat generates organic functionalities that could be used for absorptionof various metals. These resulting metal centers are suitable forelectroless metal plating. Thus, the present invention provides for theformation of a conducting layer selectively on a resin pattern bycoating the thiosulfate composition on a substrate, followed by exposureto suitable radiation, development, and deposition of metalnanoparticles or wires. By using the method of this invention, aconductive layer with a high adhesive strength, which can be similar tothe adhesive strength obtained through sputtering, can be obtained at alow cost through large-scale production.

Compared to known electroless metal plating processes, the method ofthis invention is very simple and does not require complicatedmonitoring and management of all agents. In addition, the method of thisinvention does not require a pilot line and the thiosulfate polymercomposition layer can be formed on the substrate through a stableprocess suitable for large-scale production.

For example, in some embodiments the present invention provides acapability of adsorbing fine metal nanowires and nanoparticles onto apatterned area.

The present invention can be used to provide letterpress printingplates, flexographic printing plates, offset printing plates, graphicarts films, proofing materials, photoresists, circuit board resists, andstereolithographic materials.

DETAILED DESCRIPTION OF THE INVENTION

Definitions

As used herein to define various components of the compositions andlayers, unless otherwise indicated, the singular forms “a”, “an”, and“the” are intended to include one or more of the components (that is,including plurality referents).

Each term that is not explicitly defined in the present application isto be understood to have a meaning that is commonly accepted by thoseskilled in the art. If the construction of a term would render itmeaningless or essentially meaningless in its context, the termdefinition should be taken from a standard dictionary.

The use of numerical values in the various ranges specified herein,unless otherwise expressly indicated otherwise, are considered to beapproximations as though the minimum and maximum values within thestated ranges were both preceded by the word “about”. In this manner,slight variations above and below the stated ranges can be used toachieve substantially the same results as the values within the ranges.In addition, the disclosure of these ranges is intended as a continuousrange including every value between the minimum and maximum values.

Under otherwise indicated herein, the terms “non-crosslinked thiosulfatepolymer, “copolymer”, “polymer”, “thiosulfate polymer”, “polymer havingthiosulfate groups”, “polymer having Bunte salt moieties”, and “Buntesalt polymer” are considered to be the same in the description of thepresent invention.

A “thiosulfate” group is a substituent defined by the followingStructure I.

Any compound bearing this thiosulfate group is called a “thiosulfatecompound.” When the thiosulfate group is attached to an organic moiety,the resulting compound is an “organic thiosulfate” or Bunte salt. Ifthis organic thiosulfate is a polymer (having a molecular weight of atleast 1,000), the compound is considered a thiosulfate polymer.

Unless otherwise indicated herein, the terms “composition”, “thiosulfatepolymer composition”, and “thiosulfate polymer containing composition”are intended to be the same in the description of the present invention.

Thiosulfate Polymers

In their simplest form, the thiosulfate polymers used in the presentinvention can be generally represented by the formula R—S—SO₃M, whereinR represents a suitable polymeric backbone, and M is a suitable cation.

When R is a polymer backbone, it can have multiple —S—SO₃M groupsdistributed randomly or in blocks of recurring units along the chain ofatoms forming the polymer backbone. Useful polymers that provide thebackbone are described in most detail below. The thiosulfate polymerscan be formed as vinyl polymers from ethylenically unsaturatedpolymerizable monomers using or emulsion or suspension polymerizationtechniques, or they can be condensation polymers formed usingappropriate reactive precursor compounds (for example diols with diacidsto form polyester or diamines with diols to form polyamides).

In addition, the thiosulfate polymers described in U.S. Pat. No.5,424,062 (noted above) can be used in the practice of this invention,and this disclosure is incorporate herein by reference.

M is hydrogen or a suitable monovalent cation such as a metal cation oran organic cation including but not limited to, an alkali metal ion(lithium, sodium, potassium, and cesium), ammonium, pyridinium,morpholinium, benzolium, imidazolium, alkoxypyridinium, thiazolium, andquinolinium cations. Divalent cations can be present in small amounts sothat premature crosslinking of the thiosulfate polymer is minimized.Thus, in most embodiments, M is a monovalent cation such as potassiumion or sodium ion.

Any polymer containing one or more thiosulfate moieties can be used inthe present invention. For example, suitable polymers include but arenot limited to, vinyl polymers derived at least in part frommethacrylate or acrylate ethylenically unsaturated polymerizablemonomers (known herein as “polymethacrylates” and “polyacrylates”,including both homopolymers and copolymers), polyethers, poly(vinylester)s, and polystyrenes (including homopolymers and copolymers derivedfrom styrene and styrene derivatives having one or more substituents onthe pendant benzene ring or attached along the polymer backbone). Suchthiosulfate polymers have an entirely carbon backbone. However, pendantthiosulfate groups can be incorporated into condensation polymersincluding but not limited to, polyesters, polyamides, polyurethanes,polycarbonates, polymers derived from cellulose esters, andpolysiloxanes using chemistry that would be readily known to one skilledin the art.

All of the thiosulfate polymers described herein can be mixed with anelectron-accepting photosensitizer component, or such anelectron-accepting photosensitizer component can be incorporated intothe thiosulfate polymer so that the thiosulfate polymer includes bothtypes of pendant groups (thiosulfate groups and electron-acceptingphotosensitizer components). In addition, the thiosulfate polymers canbe designed so that the same recurring units comprise pendant groupsthat comprise both electron-accepting photosensitizer groups andthiosulfate groups.

In general, useful thiosulfate polymers are optically transparent in thespectral region where the electron-accepting photosensitizer componentabsorbs. That is, the thiosulfate polymer should not have significantabsorption at the excitation wavelengths, and should not interfere withthe chemical transformation of the thiosulfate moieties. The thiosulfatepolymers can be linear, branched, or dendritic in form.

Useful thiosulfate polymers generally have a molecular weight (M_(n)) ofat least 1,000 and up to and including 1,000,000, or typically at least10,000 and up to and including 100,000, as determined using sizeexclusion chromatography (SEC).

Useful thiosulfate polymers can also have a glass transition temperature(T_(g)) of at least 20° C. and up to and including 250° C. or at least50° C. and up to and including 150° C., as determined using DifferentialScanning calorimetry (DSC).

In such polymers, a thiosulfate group or moiety can be represented bythe following Structure II:

wherein X is a suitable divalent linking group that is attached to apolymer backbone, and M is a cation as defined above.

Useful X divalent linking groups in Structure (II) include but are notlimited to, —(COO)_(n)—(Z)_(n)— wherein n is 0 or 1 and m is 0 or 1. Zcan be a substituted or unsubstituted divalent aliphatic group having 1to 6 carbon atoms including alkylene groups (such as methylene,ethylene, n-propylene, isopropylene, butylenes, 2-hydroxypropylene and2-hydroxy-4-azahexylene), which divalent aliphatic group can compriseone or more oxygen, nitrogen or sulfur atoms in the chain (such ascarbonamido, sulfonamide, alkylenecarbonyloxy, ureylene, carbonyloxy,sulfonyloxy, oxy, dioxy, thio, dithio, seleno, sulfonyl, sulfonyl, andimido), a substituted or unsubstituted arylene group having 6 to 14carbon atoms in the aromatic ring (such as phenylene, naphthalene,anthracylene, and xylylene), a substituted or unsubstituted combinationof alkylene and arylene groups such as substituted or unsubstitutedarylenealkylene or alkylenearylene groups having at least 7 and to andincluding 20 carbon atoms in the chain (such as p-methylenephenylene,phenylenemethylenephenylene, biphenylene, andphenyleneisopropylene-phenylene), or a heterocyclic ring (such aspyridinylene, quinolinylene, thiazolinylene, and benzothioazolylene). Inaddition, X can be a substituted or unsubstituted alkylene group, asubstituted or unsubstituted arylene group, in a substituted orunsubstituted arylenealkylene group or alkylenearylene group, having thesame definitions as Z. In some embodiments, it is advantageous tocovalently attach both a thiosulfate group and an electron-acceptingphotosensitizer group in the same pendant group in a single recurringunit. Thus, in Structure II, X can be or be derived from anelectron-accepting photosensitizer component as described below.

As the thiosulfate group is generally located pendant to the polymerbackbone, it can be part of an ethylenically unsaturated polymerizablemonomer that can be polymerized using conventional techniques to formvinyl homopolymers of the thiosulfate-containing recurring units, orvinyl copolymers when copolymerized with one or more additionalethylenically unsaturated polymerizable monomers. A thiosulfate polymercan include more than one type of recurring unit containing thiosulfategroup as described herein. For example, the thiosulfate polymers cancomprise different recurring units derived from different ethylenicallyunsaturated polymerizable monomers. Alternatively, the thiosulfatepolymer can be have the same or different backbone in each recurringunit, but comprise different thiosulfate groups as defined by differentX (with different “n”, “m”, or Z groups) as noted above for Structure(II).

In embodiments of the thiosulfate polymers that are vinyl polymers, thethiosulfate-containing recurring units generally comprise at least 1 mol% of all recurring units in the thiosulfate polymer, or typically atleast 15 mol % and up to and including 90 mol %, or even up to andincluding 100 mol % of all (in moles) recurring units. In mostembodiments, the thiosulfate-containing recurring units comprise atleast 15 mol % and up to and including 50 mol % of the total recurringunits in the thiosulfate polymer. For the vinyl thiosulfate polymersthat are copolymers, the remaining recurring units can be derived fromone or more ethylenically unsaturated polymerizable monomers includingbut not limited to methacrylates, acrylates, acrylamides,methacrylamides, styrene and its derivatives, vinyl ethers, vinylesters, (meth)acrylonitrile, vinyl pyrrolidones, maleimides, vinylimidazoles, and vinyl formamide. A skilled polymer chemist would be ableto choose suitable co-monomers to be used to make desired thiosulfatecopolymers within the spirit of the present invention. The amount ofrecurring units derived from these additional ethylenically unsaturatedpolymerizable monomers can be at least 10 mol % and up to and including99 mol %, or more likely at least 20 mol % and up to and including 50mol %, based on the total (moles) recurring units in the thiosulfatepolymer. In general, in the thiosulfate polymers used in this invention,the various recurring units are arranged in random order along thepolymer molecule, although blocks of certain recurring units can bearranged if desired.

Thiosulfate polymers useful in the present invention can be prepared inseveral ways using understanding and reactants available to a skilledpolymer chemist. For example, the useful thiosulfate monomers andreactive ethylenically unsaturated polymerizable co-monomers can beobtained from a number of commercial sources or readily prepared.

For example, thiosulfate-containing ethylenically unsaturatedpolymerizable monomers can be prepared from the reaction between analkyl halide and thiosulfate salt as described in the seminal teachingof Bunte, Chem. Ber. 7, 646, 1884. Thiosulfate polymers can be preparedeither from functional ethylenically unsaturated polymerizable monomersor from preformed polymers having requisite reactive groups. Forexample, if the functional ethylenically unsaturated polymerizablemonomer is a vinyl halide polymer, the functional vinyl polymerizablemonomer can be prepared as illustrated as follows:

wherein R₁ is hydrogen or a substituted or unsubstituted alkyl groupcomprising 1 to 10 carbon atoms or an aryl group, Hal represents ahalide, and X represents a divalent linking group as defined above. Theconditions for these reactions are known in the art.

Thiosulfate polymers can also be prepared from preformed polymers in asimilar manner as described in U.S. Pat. No. 3,706,706 (Vandenberg) asillustrated as follows, the disclosure of which is incorporated hereinby reference for the polymer synthetic methods:

wherein A represents the polymer backbone, Hal represents a halide, andX represents a divalent linking group as described above.

In addition, thiosulfate polymers can be prepared using the reaction ofan alkyl epoxide (on a preformed polymer or a functional monomer) with athiosulfate salt, or between an alkyl epoxide (on a preformed polymer ofa functional monomer) and a molecular containing a thiosulfate moiety(such as 2-aminoethanethiosulfuric acid), as illustrated by Thames,Surf. Coating, 3 (Waterborne Coat.), Chapter 3, pp. 125-153, Wilson etal (Eds.) and as follows:

wherein R represents a substituted or unsubstituted alkyl or arylgroups. The conditions for these reactions are known in the art andrequire only routine experimentation to complete.

In some other embodiments of this invention, the thiosulfate polymercompositions comprise a thiosulfate polymer that further comprises anelectron-accepting photosensitizer component that is acovalently-connected component. In other words, the electron-acceptingphotosensitizer component is another group that is incorporated withinthe thiosulfate polymer, for example as a pendant group connected to thepolymer backbone using a suitable linking group, in some recurring unitsof the thiosulfate polymer.

For example, useful linking groups can be any aliphatic or hydrocarbonlinking group that does not adversely affect the usefulness of thethiosulfate polymer. Such linking groups include but are not limited to,—(COO)_(n)(Z)_(m)— wherein n is 0 or l, m is 0 or 1, and Z is asubstituted or unsubstituted alkylene group having 1 to 6 carbon atoms(such as methylene, ethylene, n-propylene, isopropylene, butylenes,2-hydroxypropylene and 2-hydroxy-4-azahexylene) that can have one ormore oxygen, nitrogen or sulfur atoms in the chain, carbonamido[—C(═O)—NH—], sulfonamide [—SO₂—NH-], a substituted or unsubstitutedarylene group having 6 to 14 carbon atoms in the aromatic ring (such asphenylene, naphthalene, anthracylene and xylylene), or a substituted orunsubstituted arylenealkylene (or alkylenearylene) group having 7 to 20carbon atoms in the chain (such as p-methylenephenylene,phenylenemethylenephenylene, biphenylene andphenyleneisopropylene-phenylene). In addition, the linking group can bean alkylene group, an arylene group, vinylenecarbonyloxy[—CR═CR′—C(═O)—O—] wherein R and R′ are independent hydrogen, methyl, orethyl, acetylimino [CH₃C(═O)—N<], alkylenecarbonyloxy [for example,—CH═CH—CH₂—C(═O)—O-], alkyleneimino (for example, —CH₂—NH—),alkylenecarbonyloxy [for example, —CH₂—C(═O)—O—], benzylene,carbonyldioxy [—O—C(═O)—O—], diazo [—N═N—], and ureylene[—NH—C(═O)—NH—].

For example, the linking group can be a substituted or unsubstituteddivalent organic linking group that can have least one oxygen, sulfur,or nitrogen heteroatom in the organic linking group chain. For example,useful Z groups include but are not limited to, carbonyloxy [—C(═O)—O—],sulfonyloxy [—SO₂—O—], oxy (—O—), dioxy (—O—O—) thio (—S—), dithio(—S—S—), seleno (—Se—), sulfinyl (—SO—), sulfonyl (—SO₂—), carbonamido[—C(═O)—NH—], sulfonamide [—SO₂—NH—], substituted or unsubstitutedarylene (such as substituted or unsubstituted phenylene), substituted orunsubstituted cycloalkylene having 5 to 8 carbon atoms in the chain(such as pentylene, 1,3-hexylene, 1,4-hexylene, and3-methyl-1,4-hexylene), imido (—NH—), vinylenecarbonyloxy[—CR═CR′—C(═O)—O—] wherein R and R′ are independent hydrogen, methyl, orethyl, acetylimino [CH₃C(═O)—N<], alkylenecarbonyloxy [for example,—CH═CH—CH₂—C(═O)—O-], alkyleneimino (for example, —CH₂—NH—),alkylenecarbonyloxy [for example, —CH₂—C(═O)—O—], benzylene,carbonyldioxy [—O—C(═O)—O—], diazo [—N═N'], and ureylene[—NH—C(═O)—NH—]. Combinations of two or more of the linking groups canbe used to form a divalent linking group.

For example, the thiosulfate polymer can be a copolymer comprising, inrandom order: (a) recurring units comprising thiosulfate groups (asdefined in more detail above), and (b) recurring units comprising theelectron-accepting photosensitizer component that is derived from anelectron-accepting photosensitizer compound, for example such one ofPS-1 through PS-28 described below.

The relative amount of the (a) and (b) recurring units can varyconsiderably, but in general, (a) recurring units comprise at least 1mol % and up to and including 99.9 mol % of the total polymer recurringunits, and the (b) recurring units comprise at least 0.01 mol % and upto and including 99 mol % based on the total (moles) thiosulfate polymerrecurring units. More typically, the (a) recurring units comprise atleast 10 mol % and up to and including 75 mol % of the total thiosulfatepolymer recurring units, and the (b) recurring units comprise at least25 mol % and up to and including 90 mol % of the total thiosulfatepolymer recurring units.

When the thiosulfate polymers are copolymers comprise both thiosulfategroups and electron-accepting photosensitizer components within thepolymer molecule, such copolymers can further comprise, in random order:(c) recurring units other than the (a) and (b) recurring units. Such (c)recurring units can be derived from one or more ethylenicallyunsaturated polymerizable monomers as described above, which would bereadily apparent to a skilled worker in the art, and such (c) recurringunits can be present in an amount of at least 0.1 mol % and up to andincluding 50 mol % based on the total recurring units in the copolymer,while the (a) recurring units can be present in an amount of at least 10mol % and up to and including 50 mol %, and the (b) recurring units canbe present in an amount of at least 10 mol % and up to and including 50mol %, all based on the total (moles) recurring units in the copolymer.

In some embodiments, one or more of the (c) recurring units can comprisea pendant charged group, that is, either negative-charged andpositive-charged groups. In particular embodiments, the (c) recurringunits comprise a pendant carboxy, carboxylate, phospho, phosphonate,phosphate, sulfo, sulfonate, or sulfite group, or combinations of suchgroups in the same recurring units.

In other embodiments, the (c) recurring units are present in thethiosulfate polymer with the (a) and (b) recurring units in an amount ofup to and including 50 mol %, the (a) recurring units are present in thethiosulfate polymer in the amount of at least 1 mol %, and thethiosulfate polymer further comprises (d) recurring units that have atotal neutral charge and are present in an amount of at least 1 mol %and up to and including 49 mol %, all based on the total moles ofrecurring units in the thiosulfate polymer.

In such embodiments, the molar ratio of the (a) recurring units to the(d) recurring units can be from 1:3 to 3:1 in the thiosulfate polymer.

In still other embodiments, the thiosulfate polymer comprises (a)recurring units comprising thiosulfate groups and (c) recurring unitsthat comprise a pendant charged group in an amount of at least 0.1 mol %based on the total moles of recurring units in the thiosulfate polymer.The (b) and (d) recurring units can be absent from such embodiments.

Thiosulfate polymers comprising electron-accepting photosensitizercomponents in at least some of the recurring units can be prepared bymethods illustrated below using reactive components and conditions thatwould be readily apparent to one skilled in the art using therepresentative teaching provided below.

Thiosulfate Polymer Compositions

There are various ways to formulate the thiosulfate polymer compositionsuseful in the present invention.

In some embodiments, the thiosulfate polymer is thoroughly mixed withone or more electron-accepting photosensitizer components (describedbelow) that is a compound(s) separate from the thiosulfate polymer. Thisseparate compound(s) can be polymeric or non-polymeric. In other words,the electron-accepting compound can be a non-polymeric compound, or itcan be attached to a polymer that is not a thiosulfate polymer. Thismixture of thiosulfate polymer and one or more electron-acceptingphotosensitizer components can be supplied as a dry mixture or insolution with one or more suitable solvents, such as tetrahydrofuranacetonitrile, acetone, methyl ethyl ketone (MEK), dioxane, dimethylacetamide (DMac), and dimethyl formamide (DMF).

The thiosulfate group is generally present in the thiosulfate polymercomposition in a relatively high concentration. For example, thethiosulfate groups are present in the thiosulfate polymer(s) in thethiosulfate polymer composition to provide at least 10 mol % to andincluding 100 mol % of the recurring units of the thiosulfate polymer.In such embodiments, the electron-accepting photosensitizer componentcan be present in an amount of at least 0.001 weight % to and including20 weight % based on the total dry weight of the thiosulfate polymercomposition, for example as part of a thiosulfate polymeric layer or anarticle (described below), with the balance of the thiosulfate polymercomposition being any optional additives (described below).

As noted above, in other embodiments, the electron-acceptingphotosensitizer component is covalently attached to the thiosulfatepolymer so that this thiosulfate polymer has both thiosulfate groups andelectron-accepting photosensitizer components attached to the polymerbackbone as pendant groups or covalently connected components.

In still other embodiments, a thiosulfate polymer in solution is mixedwith metal salt to create a charge transfer complex, which chargetransfer complex behaves as a metal complex electron-acceptingphotosensitizer component in the practice of this invention.

Compounds that can be used as electron-accepting photosensitizercomponents include but are not limited to, metal complexes such ascopper sulfate, copper nitrate, nickel chloride, nickel sulfate, zincacetate, and others that would be readily apparent to one skilled in theart.

In many embodiments, the thiosulfate polymer composition has a spectralabsorption that is different than the spectral absorption of either thethiosulfate polymer or the metal complex electron-acceptingphotosensitizer component alone.

The electron-accepting photosensitizer component used in the presentinvention initiates the chemical transformation of the thiosulfategroups in the thiosulfate polymer in response to suitable radiation.Thus, the electron-accepting photosensitizer component must be capableof oxidizing the thiosulfate anion to a radical after theelectron-accepting photosensitizer component has absorbed light (thatis, photo-induced electron transfer). Thus, in some embodiments, uponabsorption of appropriate actinic radiation, the electron-acceptingphotosensitizer component is capable of accepting an electron from thereactant thiosulfate moiety. In other embodiments of the invention, uponabsorption of suitable actinic radiation, the electron-acceptingphotosensitizer component can be fragmented to provide an oxidant thatis capable of accepting an electron from the thiosulfate group.

To determine whether a compound is capable of oxidizing the thiosulfategroups in the thiosulfate polymer to provide a radical after thecompound has absorbed light, reaction energetics can be used. There arethree controlling parameters in reaction energetics: (1) the excitationenergy (E_(PS*)), (2) the reduction potential (E_(PS) ^(red)) of theelectron-acceptor photosensitizer component (PS), and (3) the oxidationpotential (E_(R) ^(ox)) of the reactant thiosulfate moiety (R) that isan electron donor. For these reactions to be energetically feasible, theenergy of the excited state should be higher or only slightly lower thanthe energy stored in the primary product, the radical ion pair,PS^(−*)R⁺*.

The excitation energy of the electron-accepting photosensitizercomponent is conveniently determined from the midpoint of the normalizedabsorption and emission spectrum of PS, if the reaction proceeds fromthe singlet excited state. However, if the reaction proceeds via thetriplet state, then the triplet energy of PS should be used as theexcitation energy.

The energy of the radical ion pair, E_(IP), is given by the followingEquation 1, wherein Δ is an energy increment that depends on the mediumpolarity and ranges from nearly zero in highly polar media to about 0.3eV in the least polar media. The oxidation (E_(R) ^(ox)) and reduction(E_(PS) ^(red)) potentials are readily obtained from conventionalelectrochemical measurements in polar solvents such as acetonitrile ormethylene chloride.E _(IP) =E _(R) ^(ox) −E _(PS) ^(red)+Δ  Equation 1Polymeric media tend to be low in dielectric constant, and as a resultwould not strongly solvate the radical ion pair. Thus, the energyincrement Δ in Equation 1 is expected to be near the maximum value, thatis, in the range of 0.2 eV to 0.3 eV. Thus, electron-acceptingphotosensitizer components with excitation energy equal to or largerthan the difference between the oxidation potential of the reactant andthe reduction potential of the acceptor, (E_(R) ^(ox)−E_(PS) ^(red)),will satisfy the energetic requirements of photoinitiating the reactionas described in the following Equation 2:E _(PS*) ≧E _(R) ^(ox) −E _(PS) ^(red)  Equation 2

It is more convenient to express the energetic requirements of theelectron-accepting photosensitizer component relative to the donor interms of a rearranged form of Equation 2 shown below as Equation 3:E _(PS*) +E _(PS) ^(red) ≧E _(R) ^(ox)  Equation 3

According to Equation 3, for the reaction to be energetically feasible,the algebraic sum of the excitation energy of the electron-acceptingphotosensitizer component and its reduction potential should beapproximately equal to or larger than the oxidation potential of thereactant. When the reactant is the thiosulfate group, which has anoxidation potential of about 1 V (vs. SCE), numerous electron-acceptingphotosensitizer components that meet the requirement of Equation 3, canbe used. Some compounds that meet the requirement of Equation 3 arelisted below in TABLE I.

In general, sum of the electron-accepting photosensitizer componentreduction potential and excitation energy is equal to or greater thanthe oxidation potential of the thiosulfate groups in the thiosulfatepolymer. For example, this sum of reduction potential and excitationenergy can be at least −1 V to and including +5 V (vs SCE), or morelikely of at least −0.1 V to and including +3 V (vs SCE). Reductionpotential and excitation energy can be determined for a given compoundfrom sources in the literature or by measuring these parameters usingcyclic voltammetry and UV-Vis spectrophotometery, respectively.

In general, derivatives from many different compounds can be used aselectron-accepting photosensitizer components for thiosulfate groupreactants, provided that the energetic requirements discussed above (inEquation 3) are satisfied. For example, the electron-acceptingphotosensitizer component can be an organic photosensitizer N-containingheterocyclic compound such as azinium salts, oxyazinium salts,thiazolium salts, pyrylium salts, naphthalene diimides, and naphthaleneimides.

Representative electron-accepting photosensitizer components include butare not limited to, cyano-substituted carbocyclic aromatic compounds orcyanoaromatic compounds (such as 1-cyanonaphthalene,1,4-dicyanonaphthalene, 9,10-dicyanoanthracene,2-t-butyl-9,10-dicyanoanthracene, 2,6-di-t-butyl-9,10-dicyanoanthracene,2,9,10-tricyanoanthracene, 2,6,9,10-tetracyanoanthracene), aromaticanhydrides and aromatic imides (such as 1,8-naphthylene dicarboxylic,1,4,6,8-naphthalene tetracarboxylic, 3,4-perylene dicarboxylic, and3,4,9,10-perylene tetracarboxylic anhydride or imide), condensedpyridinium salts (such as quinolinium, isoquinolinium, phenanthridinium,acridinium salts), and pyrylium salts. Useful electron-acceptingphotosensitizer components that involve the triplet excited stateinclude but are not limited to, carbonyl compounds such as quinones (forexample, benzo-, naphtho-, and arthro-quinones with electron withdrawingsubstituents such as chloro and cyano). Ketocoumarins especially thosewith strong electron withdrawing moieties such as pyridinium can also beused as electron-accepting photosensitizer components. These compoundscan optionally contain substituents such as methyl, ethyl, tertiarybutyl, phenyl, methoxy, and chloro groups that can be included to modifyproperties such as solubility, absorption spectrum, and reductionpotential. The electron-accepting photosensitizer components used in thepresent invention can also be derived from the noted compounds.

These electron-accepting photosensitizer components can be used asindividual materials in the thiosulfate polymer compositions, or theycan be used as precursors from which electron-accepting photosensitizercomponents are derived for covalent attachment to the thiosulfatepolymers useful in the present invention, for example in recurring unitsderived from ethylenically unsaturated polymerizable monomers asdescribed above Attachment of the electron-accepting photosensitizercomponent to the thiosulfate polymer can improve the efficiency of themethods of this invention used for photo-patterning by allowing thethiosulfate components and the electron-accepting photosensitizercomponent in close proximity. In addition, attaching theelectron-accepting photosensitizer components to the thiosulfate polymercan also reduce insolubility of the unattached corresponding components.PS-22 to PS-24 compounds listed below in TABLE I are examples ofelectron-accepting photosensitizer components comprising ethylenicallyunsaturated polymerizable vinyl groups, which components can beincorporated into thiosulfate polymers as described above.

Other useful electron-accepting photosensitizer components are inorganicsalts or complexes such as transition metal salts and complexes, whereinthe metal salts can include but are not limited to, copper sulfate,nickel chloride, copper nitrate, zinc acetate, ferric chloride, andothers that would be readily apparent to one skilled in the art usingthe teaching herein.

For example, the thiosulfate polymer composition can further comprise acomplexing metal ions, such as stannous, ferric, cobalt, silver,palladium, platinum, or gold ions.

Representative non-polymeric electron-accepting photosensitizercomponents PS-1 to PS-28 are shown in the following TABLE I:

TABLE I

PS-1

PS-2

PS-3

PS-4

PS-5

PS-6

PS-7

PS-8

PS-9

PS-10

PS-11

PS-12

PS-13

PS-14

PS-15

PS-16

PS-17

PS-18

PS-19

PS-20

PS-21

PS-22

PS-23

PS-24

PS-25

PS-26

PS-27

PS-28

The thiosulfate polymer composition can also contain optionalingredients such as a plasticizer, preservative, or surfactant, inindividual or cumulative amounts of up to and including 15 weight %,based on total thiosulfate polymer composition weight.

There are various ways to obtain thiosulfate polymer compositions. Thefollowing ways are representative but not meant to be limiting.

1) A non-crosslinked thiosulfate polymer can be thoroughly mixed with anappropriate electron-accepting photosensitizer component as a separatecompound in an appropriate solvent of mixture of solvents.

2) A thiosulfate polymer can be thoroughly mixed with at least 0.1weight % and up to and including 15 weight % of an appropriateelectron-accepting photosensitizer component and an equimolar amount ofa tetraalkyl ammonium halide salt in an appropriate solvent or mixtureof solvents. Organic solvents that are soluble in water are useful inthis mixture, including but not limited to tetrahydrofuran, acetone,ethyl methyl ketone, N-methylpyrrolidone, dimethyl acetamide, andcyclopentanone. The exact amount of electron-accepting photosensitizercomponent depends upon its extinction coefficient and the eventual use.

3) An ethylenically unsaturated ethylenically polymerizable monomercomprising an electron-accepting photo sensitizer component can beco-polymerized one or more monomers at least one of which includes therequired thiosulfate group.

4) An ethylenically unsaturated ethylenically polymerizable monomercomprising an electron-accepting photosensitizer component bearingcovalently attached thiosulfate group can be co-polymerized one or moreethylenically unsaturated polymerizable monomers.

5) A thiosulfate polymer in solution can be mixed with a metal salt tocreate a charge transfer complex.

A useful amount of resulting electron-accepting photosensitizercomponent in the resulting thiosulfate polymer can be at least 0.1 mol %and up to and including 10 mol % in relation to the molar amount ofthiosulfate groups present in the thiosulfate polymer, composition, orpolymeric layer. The exact amount of electron-accepting photosensitizercomponent can depends upon its extinction coefficient and application.This polymer can also comprise recurring units derived from otherethylenically unsaturated polymerizable monomers having differentgroups.

In some embodiments, the thiosulfate polymer composition can furthercomprise tetraalkyl ammonium ions including the same or different alkylgroups having 1 to 10 carbon atoms.

In such embodiments, the thiosulfate polymer can be a copolymercomprising, in random order: (a) recurring units comprising thiosulfategroups, (b) recurring units comprising the electron-acceptingphotosensitizer component, and additional (c) recurring units comprisingpendant charged groups.

Articles

The thiosulfate polymer composition can be in the form of aself-supporting slab or disk. It can also be a solution that is appliedto or disposed onto a suitable support or substrate including but notlimited to, polymeric films, glass, metals, stiff papers, or alamination of any of these materials, and the support or substrate canbe formed in any suitable shape. Polymeric film supports can bematerials such as poly(ethylene terephthalate), poly(ethylenenaphthalate), polycarbonate, polystyrene, cellulose acetate, inorganicpolymeric materials such as certain glasses. In some embodiments, thesupport comprises a polyester or glass.

Thus, articles described herein can comprise a substrate having disposedthereon a coating comprising any of the thiosulfate polymercompositions, either in a continuous arrangement or in a predeterminedpattern.

The support can also be a cylindrical surface and the thiosulfatepolymer composition can be applied to its outer surface. The use of suchcylinders is described for example in U.S. Pat. No. 5,713,287 (Gelbart),the disclosure of which is incorporated herein by reference.

The surface of the support or substrate can be treated in order toimprove the adhesion of the thiosulfate polymer composition thereto. Forexample, the surface can be treated by corona discharge prior toapplying the thiosulfate polymer composition. Alternatively, anunder-coating or subbing layer, such as a layer formed from ahalogenated phenol or a partially hydrolyzed vinyl chloride-vinylacetate copolymer, can be applied to the surface of the support prior toapplication of the thiosulfate polymer composition.

The thiosulfate polymer composition can be applied to the support anddried sufficiently to provide a dry thickness of at least 1 nm and up toand including 1 cm, or of at least 25 nm and up to and including 2000nm. The applied layer can be uniformly over the entire substrate surfacein a continuous or discontinuous manner, and it can be disposed in arandom or predetermined pattern.

Methods of the Invention

During use of the thiosulfate polymer composition described herein, itis exposed to suitable radiation (such as UV or visible light) in apredetermined imagewise fashion, and the thiosulfate polymer compositioncan be exposed through a mask if desired, and the resulting exposed ornon-exposed regions can be treated in a suitable manner to provideeither a negative-working or positive-working pattern. When using alaser to expose (or image) the thiosulfate polymer composition, a diodelaser is particularly useful because of its reliability and lowmaintenance, but other lasers such as gas or solid state lasers can alsobe used. The combination of power, intensity, and exposure time forlaser imaging would be readily apparent to one skilled in the art.

As noted above, the thiosulfate moiety in the thiosulfate polymer iscapable of undergoing a chemical transformation from photochemical oneelectron oxidation, thus causing a change in solubility in the exposedregions of the exposed thiosulfate polymer composition that can beprovided on a suitable substrate. The photo-induced electron transferreaction forms a product species, a process that defines thecross-linking event. New chemical bonds are formed between individualreactant moieties that results in a desired change in solubility in theexposed regions.

Scheme I below illustrates the photoinduced electron transfer inducedreaction of the thiosulfate groups in the thiosulfate polymer. After theelectron-accepting photosensitizer component (PS) has absorbedradiation, it oxidizes the thiosulfate ion to form a thiosulfurylradical and an electron-accepting photosensitizer component radicalanion (PS). In a subsequent step, the thiosulfuryl radical (—S—SO₃)fragments to generate a sulfur centered radical (—S) that dimerizes withanother nearby sulfur radical to form a disulfide (—S—S—) bond (SchemeI). When the thiosulfate groups are in the polymer matrix, it isbelieved that the formation of the disulfide (—S—S—) bonds provide thechange in polymer solubility.

With the product formation, besides the change in solubility, changes insurface energy, glass transition temperature, and other opticalproperties such as refractive index and fluorescence properties, canalso occur.

The thiosulfate polymer composition can be applied to a suitablesubstrate using any suitable means such as spray coating, roller orhopper coating, blade coating, spin coating, gravure coating,flexographic printing, or continuous or drop on demand ink jet printing.If the thiosulfate polymer composition comprises a solvent, it can beevaporated or otherwise removed for example at 50° C. to 70° C. using asuitable means such a heater or dryer. The conditions for thiosulfatepolymer composition application and solvent removal would be readilyapparent to a skilled artisan in manufacturing with suitable knowledgeof the substrate and solvent properties. During drying, the temperatureshould remain below 120° C. to prevent thermal decomposition of thethiosulfate groups in the thiosulfate polymer.

During the methods of use, the thiosulfate polymer compositions andarticles described herein can be exposed to suitable radiation, forexample having a wavelength of at least 200 nm and up to but less than725 nm, depending upon the spectral absorption of the electron-acceptingphotosensitizer component used in those embodiments.

A polymeric layer of the non-crosslinked thiosulfate polymer can beprovided and irradiated with the noted radiation to photochemicallyreact the thiosulfate polymer to provide a crosslinked polymer havingdisulfide groups in a predetermined pattern in the polymeric layer. Thepredetermined pattern can be provided using a mask layer, “digitalirradiation” (as used in digital printing), or flexographic printing.Irradiation can be focused in the foreground or background areas of thethiosulfate polymer layer, depending upon whether the thiosulfatepolymer layer is intended to function as a negative-working orpositive-working system. When a laser is used to irradiate thethiosulfate polymer layer, it is can be a diode laser providing aradiation of a desired wavelength, because of the reliability and lowmaintenance of diode laser systems, but gas or solid state lasers canalso be used. The combination of power, intensity and exposure time forlaser imaging would be readily apparent to one skilled in the art.Irradiation efficiency can be improved when the thiosulfate polymerlayer is thicker or also comprises one or more electron-acceptingphotosensitizer components (as defined above), either as separatecompounds or as part of the thiosulfate polymer.

As noted above, the reactant thiosulfate group in the thiosulfatepolymer is capable of undergoing a chemical transformation upon exposureand one electron oxidation, thus causing the change in solubility in theexposed regions of the thiosulfate polymer layer. The exposed areas ofthe thiosulfate polymer are crosslinked through generated disulfidebonds while the areas outside of the predetermined pattern remainnon-crosslinked. The thiosulfate groups undergo a photo-induced electrontransfer reaction to ultimately form a product species, a process thatdefines the cross-linking event. With the product formation, there areaccompanying changes in solubility, surface energy, glass transitiontemperature, and other optical properties such as refractive index,fluorescence properties, or absorption spectrum. New chemical bonds, forexample disulfide bonds, are formed between individual reactant moietiesthat results in a change in solubility.

Irradiation energy can be varied depending upon the thickness of thethiosulfate polymer layer, the concentration of thiosulfate groups inthe irradiated thiosulfate polymer(s), the concentration of anelectron-accepting photosensitizer component, the energy level of theirradiation, and other factors that would be readily apparent to oneskilled in the art. For example, useful laser irradiation with awavelength of at least 200 nm to and including 1200 nm can be carriedout using energy of at least 0.01 mJ/cm².

After the irradiation and formation of crosslinked polymer, thethiosulfate polymer layer can be washed with a suitable solvent (such asan aqueous solution) to remove the non-crosslinked thiosulfate polymerwhile leaving the crosslinked polymer in the predetermined pattern.Water is a convenient solvent for removing (developing) thenon-crosslinked thiosulfate polymer but other aqueous solutions are alsouseful, and they can be used at temperature or heated up to and belowthe boiling point of the aqueous solvent.

The remaining crosslinked thiosulfate polymer (with disulfide bonds) canthen be treated with a suitable disulfide-reactive material. The mostimportant reaction of disulfide bonds is their cleavage, for exampleusing a reduction reaction. A variety of reductants can be used. Inbiochemistry, thiols such as mercaptoethanol (ME) or dithiothreitol(DTT) can be used as reductants. In organic synthesis, hydride agentsare typically employed for scission of disulfides, such as borohydride.Alkali metals and certain transition metals such as gold, silver, andcopper also cleave disulfide bonds. Such reactions can be used toselectively deposit silver, gold, or copper metals onto crosslinkedpolymers (having disulfide bonds) to make conductive patterns.

For example, the crosslinked thiosulfate polymer (with disulfide bonds)can be treated with a metal or metal salt that is reactive with thedisulfide bonds. Examples of such metals and metal salts include but arenot limited to, silver, gold, copper, nickel and iron, or salts thereof.Mixtures of metals or metal salts could be used. The treated crosslinkedthiosulfate polymer can then be used to pattern conductive coatings,pattern surface energy modulation, and pattern bioreactivity.

Alternatively, a method of this invention comprises:

-   -   providing a polymeric layer comprising a non-crosslinked        thiosulfate polymer that also comprises pendant organic charged        groups,    -   photochemically reacting the non-crosslinked thiosulfate polymer        to provide polymer layer areas comprising a crosslinked polymer        having disulfide groups in the polymeric layer,    -   optionally washing the polymeric layer to remove any        non-crosslinked thiosulfate polymer while leaving the        crosslinked polymer in the polymeric layer, and    -   contacting the polymeric layer with a dispersion of metal        nanoparticles to complex the metal nanoparticles with the        crosslinked polymer having disulfide groups.

For example, this method can comprise contacting the polymeric layerwith a dispersion of gold, silver, platinum, palladium, or coppernanoparticles.

In addition, the method can comprise photochemically reacting thenon-crosslinked thiosulfate polymer to provide polymer layer areas in apredetermined pattern that comprise a crosslinked polymer havingdisulfide groups.

In such methods, the polymeric layer can comprise an electron-acceptingphotosensitizer component. Washing the polymeric layer to remove thenon-crosslinked thiosulfate polymer can be carried out using an aqueoussolution such as water.

In some embodiments, metal can be sequestered in the thiosulfate polymercomposition after the polymeric layer is washed to removenon-crosslinked thiosulfate polymer. The remaining crosslinkedthiosulfate polymer in the thiosulfate polymer layer can be treated witha metal ion solution to incorporate ions of the metal in the thiosulfatepolymer layer areas comprising the crosslinked polymer. Metal ionsuseful for this purpose include but are not limited to, gold, silver,nickel, and copper ions, and can be supplied in a suitable aqueoussolution (also include metal ion dispersions). The incorporated metalions are reacted (reduced) to form nanoparticles of metal, and the metalnanoparticles can be electroless plated to obtain a coating of the metalin the predetermined pattern.

Yet another method relates to the hairdressing industry in which shapedhair (for example, human hair that has been shaped by a hairdresser) istreated or contacted with the thiosulfate polymer composition comprisinga thiosulfate polymer and an electron-accepting photosensitizercomponent having spectral absorption of up to and including 1200 nm. Thethiosulfate polymer composition used in this method is typically in anaqueous solvent so it can be readily applied to shaped hair for asuitable period of time and washed or rinsed out when the treatment iscompleted. The thiosulfate polymer composition can be applied to all oronly portions of the customer's shaped hair. This treatment of hair issometimes known in the art as “setting” or “fixing” hair.

Once the thiosulfate polymer composition has been applied to the shapedhair, the contacted shaped hair (portion of shaped hair to which thecomposition has been applied) can be exposed to suitable radiation toprovide disulfide groups in the thiosulfate polymer that are reactivewith protein in the contacted shaped hair. Such radiation is typicallyavailable from fluorescent or incandescent light sources.

In general, a skilled hairdresser would know how to choose suitable timeand temperature conditions to achieve the desired properties in theshaped hair of a customer. The shaped and treated hair can then be driedas is common in this industry.

Thus, in some other embodiments, the thiosulfate polymer composition canbe used to shape hair in a hair treatment. Thus, a method for shapinghair comprises:

-   -   transforming hair into shaped hair,    -   contacting the shaped hair with a composition comprising a        thiosulfate polymer comprising an electron-accepting        photosensitizer component having spectral absorption of up to        and including 1200 nm, as described herein, and    -   exposing the contacted shaped hair with radiation to provide        disulfide groups in the thiosulfate polymer that are reactive        with protein in the contacted shaped hair.

For example, contacting the shaped hair can be carried out for at least0.5 minute and up to and including 20 minutes at a temperature of atleast 20° C. Other details for shaping hair with the thiosulfate polymercomposition would be readily apparent to one skilled in the art asdescribed in various publications directed to shaping hair, such as inU.S. Pat. No. 5,071,641 (noted above) and U.S. Pat. No. 5,424,062 (notedabove) the disclosures of which are incorporated herein.

The non-crosslinked thiosulfate polymer can be washed out of the shapedhair at a later time using any aqueous solution including a shampoo orconditioner.

For treating shaped hair, the thiosulfate polymer composition canadditionally contain any or all of the following components commonlyused in the hairdressing industry such as various protein dispersions,emulsifying agents, swelling agents (such as propylene glycol monomethylether), pH adjusting compounds, buffers, cosmetic agents (such asperfumes) lanolin derivatives, and thickening agents. For example, U.S.Pat. No. 5,242,062 (noted above) describes various additives useful inhair treating compositions in Columns 4 and 5, which disclosure isincorporated herein by reference.

The thiosulfate polymer composition that is useful for treating shapedhair can be provided in diluted or concentrated solutions or dispersions(emulsions), as well as creams, gels, or pastes. The compositions can bedelivered from bottles, pressurized aerosol cans, or any other suitablecontainer.

Methods for Applying and Imaging Thiosulfate Polymer Compositions

The methods of the present invention can be carried out in several waysto provide articles of the present invention. For example:

1) A thiosulfate polymer composition can be applied to a suitablesubstrate;

2) The thiosulfate polymer composition coating can be then dried at fromat least 40 and up to and including 50° C. for at least 1 and up to andincluding 60 minutes;

3) The dried coating can be then exposed to radiation at an appropriatewavelength through a mask for an appropriate length of time (time ofexposure is determined by the extinction coefficient of theelectron-accepting photosensitizer component being used and thickness ofthe coating); and

4) The thiosulfate polymer composition in the unexposed areas of thecoating can be washed away, if desired, using an aqueous solution suchas plain water, and the thiosulfate polymer composition that is removedcan be reused.

In some embodiments, metals can be deposited onto an imaged thiosulfatepolymer composition coating as the metal will deposit only in imagedareas. There are multiple ways to achieve selective area deposition of ametal.

One method can comprise:

Applying a thiosulfate polymer composition to a suitable substrate;

Drying the coating at from 40 to 50° C. for at least 1 and up to andincluding 60 minutes;

Exposing the dried thiosulfate polymer composition coating to radiationof an appropriate wavelength through a suitable mask for an appropriatelength of time (time of exposure is determined by extinction coefficientof the electron-accepting photosensitizer component being used andthickness of the coating);

Optionally washing the dried and exposed composition coating with wateror another aqueous solution to wash away composition in unexposed(non-imaged) areas to obtain an image on the substrate; and thecomposition that is washed away can be reused;

Applying a conductive metal precursor salt solution to the exposed(imaged) areas on the substrate;

Adding a reducing agent to the substrate;

Optionally washing the exposed (imaged) areas on the substrate withwater or another aqueous solution; and

Depositing a suitable metal (for example from a dispersion) on exposed(imaged) areas on the substrate.

Another method comprises:

Coating a thiosulfate polymer composition onto a substrate;

Drying the composition coating at from 40 and up to and including 50° C.for at least 1 and up to and including 60 minutes;

Exposing the dried coating to radiation of an appropriate wavelengththrough a mask for an appropriate length of time (time of exposure isdetermined by extinction coefficient of the electron-acceptingphotosensitizer component being used and thickness of the driedcoating);

Washing the dried coating with water or another aqueous solution to washaway thiosulfate polymer composition in the unexposed (non-imaged) areasto obtain an image on the substrate, and the thiosulfate polymercomposition that is washed away from the unexposed (non-imaged) areascan be reused;

Dipping the imaged substrate into or applying a metal nanoparticlecontaining solution; and

Optionally, washing the substrate with an aqueous solution so that metalnanoparticles are deposited only on the imaged (exposed) areas on thesubstrate.

In yet another embodiment, the method can include:

Coating a thiosulfate polymer composition onto a substrate;

Drying the thiosulfate polymer composition coating at from 40 and up toand including 50° C. for at least 1 and up to and including 60 minutes;

Exposing the dried thiosulfate polymer composition to radiation ofappropriate wavelength through a mask for appropriate length of time(the time of exposure is determined by the extinction coefficient of theelectron-accepting photosensitizer component being used and thickness ofthe coating);

Washing the dried thiosulfate polymer composition with water or anotheraqueous solution to wash away thiosulfate polymer composition in theunexposed (non-imaged) areas to obtain an image on the substrate, andthe thiosulfate polymer composition that is washed away from theunexposed (non-imaged) areas can be reused.

Dipping or contacting the imaged substrate with a conductive metalprecursor salt solution for an appropriate length of time; and

Washing the imaged substrate with a solution of a reducing agent so thatmetal nanoparticles are formed only in the imaged areas on thesubstrate.

Also provided is a method for electroless plating using the thiosulfatepolymer composition. Currently, electroless metal plating treatment canbe used to form a conductive coating film on an insulating object (forexample, an insulative layer). The electroless metal plating treatmentcan be carried out through a procedure having the following steps.

A conditioning step can be carried out using various surfactants toclean a substrate surface and to enable the surface to carry charges. Acatalyst-coating step can be carried out using a tin/palladium colloidbath. An activation step can be then carried out using hydrofluoric acidor another strong acid to activate the catalyst colloid that is adsorbedon the substrate surface. Electroless metal plating can then be carriedout using a plating bath containing a reducing agent such as formalin.When the substrate for the electroless metal plating treatment is aprinted circuit board for example, carrying a pattern, the pattern canbe formed with various methods, such as, but not limited to, thesubtractive method, semi-additive method, and full-additive method.

Other methods, such as primer treatment using palladium or silvercatalyst can also be used. In the primer treatment, a metal catalyst isintroduced into a resin material containing solvent and inorganicfiller. The resin material is coated onto a substrate to form a resinfilm containing a catalyst. Then, electroless metal plating is carriedout to form a conductive film. The primer treatment is mainly used on aplastic surface for the purpose of electromagnetic interference (EMI)shielding.

In the semiconductor field, sputtering and chemical vapor deposition(CVD) are more commonly used for the formation of a conductive layer andthe manufacturing technology has been established.

Moreover, a technology of introducing an organic metal salt withcatalytic activity into a resin material and then forming a conductingfilm with the resin material is disclosed in U.S. Pat. No. 5,059,242(Firmstone et al.) and has been used in the process of electrodeformation.

In electroless metal plating processes, the insulating resin material inthe printed circuit board and semiconductor device is first treated withdry etching or by using an agent such as permanganic acid to generate arough surface and to improve wettability. Then, electroless copperplating or electroless nickel plating can be conducted to form aconducting layer on the surface of the resin material.

However, it is very difficult to introduce a carboxyl group or ahydroxyl group into the resin matrix of a highly reliable insulatingresin material. The carboxyl group or hydroxyl group may reduce thereliability of the insulating resin material. As a result, theconducting layer formed through electroless metal plating has lowadhesive strength to the surface of the insulating resin material.Moreover, for the materials not suitable for generating these anchoringgroups, such as glass or ceramics to improve the attachment of a metalconductive layer, the metal conductive layer formed through electrolessmetal plating will also have low adhesive strength to the surface.

In the process of forming a conductive layer on a base material,currently the surface of the base material is first treated with oxygenplasma and then the conductive layer is formed with sputtering.Moreover, a conductive layer with the required thickness can be formedby this method by further electrolytic metal plating. However, althoughsputtering is a standard method for the formation of a thin layer, theprocess of sputtering usually takes a long period of time and the metaltarget is expensive. Therefore, the cost of the sputtering process isrelatively high.

On the other hand, the method for the formation of a conductive layerwith an organic metal salt uses a resinate compound of palladium,silver, or platinum. Such compound can be dissolved in water or anorganic solvent and the substrate to be coated is dipped into thesolution to form a coating layer of the resinate compound. Then, thermaldecomposition of the resinate compound generates a metal thin layer onthe substrate to be coated. Finally, electroless or electrolytic metalplating can be carried out to form a conductive layer. By using thismethod, however, the metal coating layer obtained has poor uniformity.In fact, the metal powder is simply attached to the surface of thesubstrate to be coated and the attachment is not very strong. In orderto solve the problem, a paste is prepared by introducing the metalresinate into a synthetic resin material, which is then coated on thesubstrate to form a uniform coating layer. The paste is widely used tofill holes on printed circuit boards and form electrodes on LCD throughscreen printing.

However, the conducting paste is not suitable for semiconductors andsemiconductor packages as well as other purposes requiring a highreliability. Moreover, it is very difficult to form fine lines throughscreen printing of the paste. In other words, when using an organicmetal salt in the formation of electronic devices, a paste can be firstprepared by introducing an organic metal salt to a synthetic resinmaterial and coating it onto a substrate through screen printing,followed by sintering to convert the organic metal salt to thecorresponding metal. In this process, the sintering temperature must behigher than the thermal decomposition temperature of the organic metalsalt (at least 300° C.) to remove the synthetic resin material.Therefore, when the synthetic resin material is completely removed, onlythe metal pattern remains. However, when the method is used in theformation of semiconductor packages, since the base body ofsemiconductor packages is made of a composite material of epoxy resinreinforced with glass fiber, the high temperature used in the sinteringstep will cause thermal damage, such as deformation or cracks, on thebase body. In addition, since the synthetic resin material is completelyremoved in the sintering step, various defects, such as pinholes or wirebreakage can be generated in the metal pattern obtained after sintering.In order to avoid these problems, a paste with a high metal content canbe used. More specifically, when using a paste containing a goldresinate to form a gold wire, the gold content in the paste must be ashigh as 25 weight % and the sintering temperature about 500° C. In otherwords, the sintering step in the coating method will cause severe damageto the substrate to be coated. In order to form a metal pattern with ahigh reliability, the content of the expensive metal in the paste shouldbe increased significantly, resulting in high production costs.

A purpose of this invention is to solve the problems mentioned above andto provide a thiosulfate polymer composition after imaging step thatforms an organic functionality where metal nanoparticles can beselectively absorbed. In a separate step, these metal centers can act asseed sites for electroless metal plating.

The electroless metal plating method can include any commonly usedelectroless metal plating for depositing a metal selected from copper,nickel, gold, tin, zinc, silver, and cobalt as well as an alloy of thesemetals. There is no special limitation on the metal, plating bath, andplating conditions used in the electroless metal plating treatment.

The metal element used can be determined based on the electroless metalplating treatment. Any metal element can be used for the purpose as longas the metal element is able to provide a catalytic activity of metaldeposition suitable for electroless metal plating. Examples of thecatalytic metal element include but are not limited to, palladium,silver, platinum, rhodium, indium, and ruthenium. In consideration ofproduction cost and plating efficiency, tin or silver is particularlyuseful as the catalytic metal element for electroless metal plating of acopper, nickel, or nickel alloy.

For example, a method can comprise:

Providing a photolithographic pattern-forming thiosulfate polymercomposition of this invention as a coating in a multilayered integralbody that comprises: (a) a substrate; (b) a photosensitive layer formedon one surface of the substrate (a), the photosensitive layer formedfrom the thiosulfate polymer composition;

Exposing the coating provided above to actinic radiation;

Optionally washing away the coatings from the first two steps using anaqueous solution (such as water); and

Dipping the coating remaining from the prior step into a nanoparticlesolution.

The present invention provides at least the following embodiments andcombinations thereof, but other combinations of features are consideredto be within the present invention as a skilled artisan would appreciatefrom the teaching of this disclosure:

1. A method comprising:

-   -   providing a polymeric layer comprising a non-crosslinked        thiosulfate polymer that also comprises pendant organic charged        groups,    -   photochemically reacting the non-crosslinked thiosulfate polymer        to provide polymer layer areas comprising a crosslinked polymer        having disulfide groups in the polymeric layer,    -   optionally washing the polymeric layer to remove any        non-crosslinked thiosulfate polymer while leaving the        crosslinked polymer having disulfide groups in the polymeric        layer, and    -   contacting the polymeric layer with a dispersion of metal        nanoparticles to complex the metal nanoparticles with the        crosslinked polymer having disulfide groups.

2. The method of embodiment 1, comprising contacting the polymeric layerwith a dispersion of gold, silver, platinum, palladium, or coppernanoparticles.

3. The method of embodiment 1 or 2, comprising photochemically reactingthe non-crosslinked thiosulfate polymer to provide polymer layer areasin a predetermined pattern that comprise a crosslinked polymer havingdisulfide groups.

4. The method of any of embodiments 1 to 3, wherein the polymeric layerfurther comprises an electron-accepting photosensitizer component.

5. The method of any of embodiments 1 to 4, wherein washing thepolymeric layer to remove the non-crosslinked thiosulfate polymer iscarried out using an aqueous solution.

6. The method of any of embodiments 1 to 5, wherein the polymeric layerfurther comprises an electron-accepting photosensitizer component thatis a covalently-connected component of the non-crosslinked thiosulfatepolymer.

7. The method of any of embodiments 1 to 6, wherein the non-crosslinkedthiosulfate polymer is a copolymer comprising, in random order: (a)recurring units comprising thiosulfate groups, and (b) recurring unitscomprising an electron-accepting photosensitizer component.

8. The method of embodiment 7, wherein the copolymer comprises, inrandom order, (c) recurring units other than the (a) and (b) recurringunits, which (c) recurring units comprise a pendant charged group, andthe (c) recurring units being present in an amount of at least 0.1 mol%, based on the total recurring units in the copolymer.

9. The method of embodiment 8, wherein the (c) recurring units comprisea pendant carboxy, carboxylate, phospho, phosphonate, phosphate, sulfo,sulfonate, or sulfite group.

10. The method of embodiment 8 or 9, wherein the (c) recurring units arepresent in the copolymer in an amount of up to and including 50 mol %,the (a) recurring units are present in the copolymer in an amount of atleast 1 mol %, and the copolymer further comprises (d) recurring unitsthat have a total neutral charge and are present in an amount oft least1 mol % and up to and including 49 mol %, all based on the totalrecurring units in the copolymer.

11. The method of any of embodiments 1 to 10, wherein the polymericlayer further comprises an electron-accepting photosensitizer componentin an amount of at least 0.1 mol % and up to and including 10 mol %, inrelation to the molar amount of thiosulfate groups present in thepolymeric layer.

12. The method of any of embodiments 1 to 11, wherein the polymericlayer further comprises an electron-accepting photosensitizer componentthat is a compound separate from the non-crosslinked thiosulfatepolymer.

13. The method of any of embodiments 1 to 12, wherein the polymericlayer further comprises an electron-accepting photosensitizer componentthat is an organic photosensitizer N-containing heterocyclic compound.

The following Examples are provided to illustrate the practice of thisinvention and are not meant to be limiting in any manner.

Synthesis 1: Preparation of Poly(vinyl benzyl thiosulfate sodiumsalt-co-methyl methacrylate)

A representative thiosulfate polymer useful in the practice of thepresent invention was prepared as follows:

Vinyl benzyl chloride (10 g, 0.066 mol), methyl methacrylate (26.23 g,0.262 mol), and AIBN (1.08 g, 7 mmol) were dissolved 180 ml of toluene.The resulting solution was purged with dry nitrogen and then heated at65° C. overnight. After cooling the solution to room temperature, it wasdropwise added to 2000 ml of methanol. The resulting white powderycopolymer was collected by filtration and dried under vacuum at 60° C.overnight. 111 NMR analysis indicated that the resulting copolymercontained 30 mol % of recurring units derived from vinyl benzylchloride.

A sample of this copolymer (18 g) was dissolved in 110 ml ofN,N-dimethyl formamide (DMF). To this solution was added sodiumthiosulfate (9 g) and 20 ml of water. Some polymer precipitated out. Thecloudy reaction mixture was heated at 70° C. for 24 hours. After coolingto room temperature, the hazy reaction mixture was transferred to adialysis membrane and dialyzed against water. A small amount of theresulting polymer solution was freeze dried for elemental analysis andthe rest was stored and used as a solution. Elemental analysis indicatedthat all the benzyl chloride groups in the copolymer were converted tosodium thiosulfate salt to provide a thiosulfate polymer useful in thepresent invention.

Synthesis 2: Preparation ofN-Butyl-N′-[2-(ethoxy-2-acrylate)ethyl]-1,4,5,8-naphthalenetetracarboxylicdiimide

A representative ethylenically unsaturated monomer useful to providethiosulfate polymers was prepared as follows:

Step 1-Synthesis of the monopotassium salt (half anhydride), 1-potassiumcarboxylate-8-carboxylic acid naphthalene-4,5-dicarboxylic anhydride:

A 12-liter, four-neck round bottom flask fitted with a mechanicalstirrer and a condenser was charged with potassium hydroxide (454 g,7.60 mol) and water (6 liters), followed by the addition of1,4,5,8-naphthalenetetracarboxylic dianhydride (462 g, 1.72 mol). Thereaction mixture was stirred for 1 hour and a clear solution resulted.Phosphoric acid, 85% (613 g 5.2 mol) in water (900 ml) was added over 45minutes, the reaction solution was stirred overnight, and the resultingsolid product was collected by filtration (yield close to 100%.) Thespectral data were consistent with its assigned structure.

Step 2-Synthesis of monoimide,naphthalenetetracarboxylic-1,8-N-butylimide-4,5-anhydride:

A 12-liter, four-neck round bottom flask fitted with a mechanicalstirrer and a condenser was charged with the monopotassium salt fromStep 1 (169.2 g, 0.52 mol) and water (5 liters) to give a milkybrown-colored suspension. Butyl amine (240 g, 3.12 mol) was added all atonce and a clear amber-colored solution was formed. The reactionsolution was heated to 90-95° C. for 1 hour. Concentrated hydrochloricacid (690 ml) dissolved in 700 ml of water was added dropwise to the hotreaction solution and heating was continued for 2 hours. During theaddition, the temperature did not exceed 95° C. Heat was removed and thereaction was allowed to stir overnight at room temperature. Theresulting precipitate was collected on a glass frit to give 150 g of thedesired product at 90% yield. Spectral data were consistent with theassigned compound structure.

Step 3-Synthesis of diimide,N-butyl-N′-[2-(2-hydroxyethoxy)-ethyl]-1,4,5,8-naphthalenetetraccarboxylicdiimide:

A 12-liter, four-neck round bottom flask fitted with a mechanicalstirrer and a condenser was charged with naphthalene butylimidemonoanhydride (434 g, 1.4 mol) from Step 2,2-(2-aminoethoxyethanol (230g, 2.2 mol), and N-methylpyrrolidone (1.2 liters). The reaction solutionwas heated to 140-150° C. for 3 hours. The reaction solution was thenallowed to cool for 30 minutes and the reaction flask was filled withmethanol and a pink-colored solid precipitated. The reaction solutionwas stirred overnight and the resulting solid was collected on a glassfrit to give 522 g of crude product (90% yield). Purification wascarried out using dichloromethane on a silica gel column, providing 313g of product (54% yield). The spectral data were consistent with theassigned compound structure.

Step 4—Coupling of naphthalene bisimide alcohol with acryloyl chloride,N-butyl-N′-[2-(ethoxy-2-acrylate)ethyl]-1,4,5,8-naphthalenetetracarboxylic diimide with acyloyl chloride:

A 5-liter, four-neck round bottom flask fitted with a mechanicalstirred, condenser and a nitrogen inlet was charged with the hydroxylether naphthalene butyl bisimide of Step 3 (246 g, 0.6 mol) andtriethylamine (73 g, 0.72 mol, 100 ml) in dichloromethane (2 liters).Acryloyl chloride (63 g, 0.7 mol, 57 ml) in dichloromethane (DCM, 150ml) was added dropwise, solubilizing the reactants and the reactionsolution was stirred at room temperature overnight. The reactionsolution was washed with 5% hydrochloride acid (200 ml), forming anemulsion. Methanol was added to break up the emulsion. The organicproducts were washed with water and dried over magnesium sulfate. Theresulting product was purified on silica column using ligroin/DCMmixture at 1/1 then increasing to 100% DCM to elute the product. Thespectral data were consistent with the assigned compound structure.

Synthesis 3: Preparation of 1,8-Naphthalimidohexyl Acrylate

A representative ethylenically unsaturated monomer useful to providethiosulfate polymers was prepared as follows:

Step 1-Synthesis of 1,8-Naphthalimidohexanol:

A 200 ml round bottom flask fitted with condenser, nitrogen inlet, andstirring magnet was charged with 1,8-naphthalic anhydride (10 g, 50.5mmole), 6-amino-1-hexanol (6 g, 51.0 mmole), and 150 ml ofN-methyl-2-pyrrolidone. The reaction mixture was warmed to 140° C. for20 hours. The reaction mixture was then cooled and poured into excessice water. A resulting brown precipitate was filtered and recrystalyzedfrom heptane to give 5 g of a tan colored solid (30% yield). Thespectral data were consistent with assigned compound structure.

Step 2-Synthesis of 1,8-Naphthalimidohexyl acrylate:

A 200 ml 3-neck round flask with a nitrogen inlet, and stirring magnetwas charged with the 1,8-naphthalimidohexanol (2.1 g, 7.1 mmole) and 60ml of anhydrous dichloromethane.

Once dissolved, triethylamine (0.9 g, 9.2 mmole) was added. To thisstirring mixture was slowly added acryloyl chloride (0.8 g, 9.2 mmole).The reaction mixture was allowed to stir at room temperature for 24hours. The reaction mixture was washed once with 10% HCl, then withwater and dried over magnesium sulfate, and the solvent was removed invacuo to provide a yellow semisolid. The resulting crude product waspurified by running it through column of silica with dichloromethane toelute the final product. The spectral data were consistent with theassigned compound structure.

Synthesis 4: Preparation of Poly(2-hydroxy-2-thiosulfate sodium saltpropyl methacrylate-co-methyl methacrylate)

The procedure of Synthesis 1 was followed using glycidyl methacrylate(18.2 g, 0.128 mol), methyl methacrylate (30.0 g, 0.300 mol),2,2′-azobis(2-methylbutyronitrile) (0.82 g, 0.004 mol), and 192 ml oftoluene. The reaction temperature was 70° C. ¹H NMR analysis indicatedthat the resulting precursor polymer contained 35 mol % of recurringunits derived from glycidyl methacrylate Analysis by size exclusionchromatography (SEC) indicated a weight average molar mass of 45,800(polystyrene standards)

The desired thiosulfate polymer was prepared as described for Synthesis1 using 30.0 g of precursor polymer, 140 ml of DMF, 16.8 g of sodiumthiosulfate, and 28 ml of water. The temperature of the reactionsolution was 70° C. for 24 hours. The thiosulfate polymer glasstransition temperature was determined to be 107.5° C. by DifferentialScanning calorimetry (DSC).

Thiosulfate Polymer 1: Preparation of Poly(vinyl benzyl thiosulfatesodium salt-co-methylmethacrylate-co-N-butyl-N′-[2-(ethoxy-2-acrylate)ethyl]-1,4,5,8-naphthalenetetracarboxylicdiimide)

The procedure of Synthesis 1 was followed using vinyl benzyl chloride(4.2 g, 0.027 mol), methyl methacrylate (8.5 g, 0.085 mol), the noteddiimide (1.1 g, 0.002 mol), 2,2′-azobis(2-methylbutyronitrile) (0.33 g,0.002 mol), and 47 ml of toluene. The reaction temperature was 70° C. 1HNMR analysis indicated that the resulting precursor polymer contained 30mol % of recurring units derived from vinyl benzyl chloride. Analysis bysize exclusion chromatography (SEC) indicated a weight average molarmass of 17,800 (polystyrene standards).

The desired thiosulfate polymer was prepared as described in Synthesis 1using 1.35 g of precursor polymer, 50 ml of DMF, 1.5 g of sodiumthiosulfate, and 10 ml of water. The temperature of the reactionsolution was 90° C. for 8 hours. The thiosulfate polymer glasstransition temperature was determined to be 99.8° C. by DifferentialScanning calorimetry (DSC).

Thiosulfate Polymer 2: Preparation of Poly(vinyl benzyl thiosulfatesodium salt-co-methyl methacrylate-co-acrylicacid-co-N-butyl-N′-[2-(ethoxy-2-acrylate)ethyl]-1,4,5,8-naphthalenetetracarboxylicdiimide)

The procedure of Synthesis 1 was followed using vinyl benzyl chloride(8.2 g, 0.053 mol), methyl methacrylate (8.5 g, 0.085 mol), acrylic acid(8.5 g, 0.119 mol), the diimide (2.3 g, 0.005 mol),2,2′-azobis(2-methylbutyronitrile) (0.76 g, 0.004 mol), and 90 ml ofdioxane. The reaction temperature was 70° C. ¹H NMR analysis indicatedthat the resulting precursor polymer contained 30 mol % of recurringunits derived from vinyl benzyl chloride. Analysis by size exclusionchromatography (SEC) indicated a weight average molar mass of 41,600(polystyrene standards).

The desired thiosulfate polymer was prepared as described in Synthesis 1using 26.1 g of precursor polymer, 285 ml of DMF, 8.5 g sodiumthiosulfate, and 57 ml of water. The temperature of reaction was held at90° C. for 8 hours. The glass transition temperature of the resultingthiosulfate polymer was determined to be 195° C. by DifferentialScanning calorimetry (DSC).

Thiosulfate Polymer 3: Preparation of Poly(vinyl benzyl thiosulfatesodium salt-co-acrylic acid-co-N-butyl-N′-[2-(ethoxy-2-acrylate)ethyl]-1,4,5,8-naphthalenetetracarboxylic diimide)

The procedure of Synthesis 1 was followed using vinyl benzyl chloride(7.3 g, 0.048 mol), acrylic acid (15.0 g, 0.21 mol), the diimide (1.9 g,0.005 mol), 2,2′-azobis(2-methylbutyronitrile) (0.76 g, 0.004 mol), and73 ml of dioxane. The reaction temperature was 70° C. 1H NMR analysisindicated that the resulting precursor polymer contained 31 mol % ofrecurring units derived from vinyl benzyl chloride. Analysis by sizeexclusion chromatography (SEC) indicated a weight average molar mass of21,400 (polystyrene standards).

The desired thiosulfate polymer was prepared as described in Synthesis 1using 20.0 g of precursor polymer, 250 ml of DMF, 6.5 g sodiumthiosulfate, and 50 ml of water. The reaction temperature was 90° C. for8 hours to provide the desired thiosulfate polymer that had a glasstransition temperature of 200° C. as determined by DSC.

Thiosulfate Polymer 4: Preparation of Poly(vinyl benzyl thiosulfatesodium salt-co-methyl methacrylate-co-1,8-naphthalimidohexyl acrylate)

The procedure of Synthesis 3 was followed using vinyl benzyl chloride(3.5 g, 0.023 mol), methyl methacrylate (7.7 g, 0.077 mol), the imide(0.5 g, 0.001 mol), 2,2′-azobis(2-methylbutyronitrile) (0.29 g, 0.002mol), and 40 ml of toluene. I H NMR analysis indicated that the desiredprecursor polymer contained 34 mol % of recurring units derived fromvinyl benzyl chloride, and analysis by size exclusion chromatography(SEC) indicated a weight average molar mass of 25,800 (polystyrenestandards).

The desired thiosulfate polymer was prepared as described in Synthesis 1using 8.0 g of precursor polymer, 40 ml of DMF, 3.9 g of sodiumthiosulfate, and 8 ml of water. The reaction temperature was held at 90°C. for 8 hours to provide the desired thiosulfate polymer that had aglass transition temperature of 111° C. as measured by DSC.

Thiosulfate Polymer 5: Preparation of Polyvinyl benzyl thiosulfatesodium salt-co-methyl methacrylate-co-acrylic naphthalimidohexylacrylate)

The procedure of Synthesis 1 was followed using vinyl benzyl chloride(3.0 g, 0.02 mol), methyl methacrylate (3.6 g, 0.036 mol), acrylic acid(3.0 g, 0.04 mop, the imide (0.4 g, 0.001 mol),2,2′-azobis(2-methylbutyronitrile) (0.28 g, 0.002 mol), and 30 ml ofdioxane. 1H NMR analysis indicated that the resulting precursor polymercontained 33 mol % of vinyl benzyl chloride, and analysis by SECindicated a weight average molar mass of 45,200 (polystyrene standards).

The desired thiosulfate polymer was prepared as described in Synthesis 3using 4.2 g of the precursor polymer, 22.5 ml of DMF, 2.1 g of sodiumthiosulfate, and 4.5 ml of water. The reaction temperature was held at90° C. to provide the desired thiosulfate polymer that had a glasstransition temperature of 119° C. as determined by DSC.

Article: Imaging Thiosulfate Polymer Composition Coating

To 1 ml of an 8 weight % solution of poly(vinyl benzyl thiosulfatesodium salt-co-methyl methacrylate) (prepared as described above inSynthesis 1) in water, was added a solution of 1.7 mg of4-phenyl-N-ethoxy pyridinium hexafluorophosphate of electron-acceptingphotosensitizer component PS-12 in 1 ml of tetrahydrofuran (THF). Theresulting thiosulfate polymer composition was stirred and thenspin-coated on glass plate (as a substrate) at 1000 rpm. The thiosulfatepolymer composition coating was protected from UV and blue light at alltimes. The thiosulfate polymer composition coating was dried for 5minutes on a hot plate at 50° C. The dry thickness of the resultinglayer was measured by spectral reflectance method using a Filmetricssingle spot measurement unit and analyzed using a FilMeasure version4.17.7 software program, and was found to be 0.8 μm. The coatedthiosulfate polymer composition was exposed to light using the mercurylamp (EXFO Acticure® spot curing system) through a mask for 10 secondsand the coated thiosulfate polymer composition was then washed withwater, followed by washing with acetone. The exposed regions of thecoated composition on the glass plate were rendered insoluble, formingthe mask image in the coated layer on the substrate, whereas the coatedthiosulfate polymer composition in the non-exposed regions of the coatedcomposition was washed away.

This example demonstrates that the thiosulfate polymer can be used toprovide an article that can be appropriately imaged to provide aphotoresist of the composition on a substrate.

Thiosulfate Polymer 7: Preparation of a Polyurethane Thiosulfate Polymer

Polycarbonate polyol M_(v), 2000 (5.4 g, 0.004 mol),2,3-dibromo-1,4-butanediol (1.9 g, 0.008 mol), and a catalytic amount ofdibutyltin diluarate were dissolved in 12 ml of tetrahydrofuran. Theresulting solution was heated at 65° C. under nitrogen. To this solutionwas added dropwise isophorone diisocyanate (2.5 g, 0.011 mol) dissolvedin 2.5 ml of tetrahydrofuran. The solution was then warmed at 75° C. for20 hours. After cooling, the solution was added dropwise to heptane. Theresulting glassy polymer was collected and dried under vacuum at 60° C.overnight. 1H NMR analysis indicated that the resulting polymercontained 24 mol % of recurring units derived from2,3-dibromo-1,4-butanediol. Analysis by size exclusion chromatography(SEC) indicated a weight average molar mass of 20,600 (polystyrenestandards).

A sample of the resulting polymer (3.0 g) was dissolved in 25 ml ofN,N-dimethyl formamide (DMF). To this solution was added sodiumthiosulfate (1.5 g) dissolved in 5 ml of water. Some polymerprecipitated out. The cloudy reaction mixture was then heated at 70° C.for 24 hours. After cooling to room temperature, the hazy reactionmixture was transferred to a dialysis membrane and dialyzed againstwater.

COMPARATIVE EXAMPLE 1 Imaging Thiosulfate Polymer Coating

To 1 ml of an 8 weight % solution of poly(vinyl benzyl thiosulfatesodium salt-co-methyl methacrylate) (prepared as described inSynthesis 1) in water, was added 1 ml of tetrahydrofuran. The resultingcomposition was stirred and then spin-coated onto a glass plate (as asubstrate) at 1000 rpm. The composition coating was protected from UVand blue light at all times. The composition coating was then dried for5 minutes on a hot plate at 50° C. The dry thickness of the coated layerwas measured as described in Inventive Example 6, and found to be 0.8The coated layer was exposed to light using a mercury lamp (EXFOActicure® spot curing system) through a mask for 10 seconds and thenwashed with water, followed by washing with acetone. All thiosulfatepolymer in the coated layer was washed away, and no image was detectedon the substrate. This example demonstrates that using a compositioncomprising only the thiosulfate polymer is ineffective to provide animageable article.

USE EXAMPLE 1 Photopatterning Thiosulfate Polymer Composition Coating

To 1 ml of an 11 weight % solution of poly(vinyl benzyl thiosulfatesodium salt-co-methyl methacrylate) (prepared in Synthesis 1) in water,0.066 weight % of 4-phenyl —N-ethoxy pyridinium hexafluorophosphate ofelectron-accepting photosensitizer component PS-12, 1.1 weight % oftetrabutylammonium chloride, and 1 ml of tetrahydrofuran was added andthen spin-coated onto a glass plate support at 1000 rpm. The resultingcoating was protected from UV and blue light at all times. The coatingwas then dried for 5 minutes on a hot plate at 50° C. The coating wasthen exposed to light using a mercury lamp through a mask for 10 secondsand then washed with water, followed by washing with acetone. Theexposed areas of the coating on the glass plate were rendered insoluble,forming an image corresponding to the mask, whereas thiosulfate polymerin the unexposed areas of the coating was washed away.

The results show that a thiosulfate composition can be used to prepare aphotoresist with an image.

USE EXAMPLE 2 Demonstration of Photoinduced Electron Transfer

To 1 ml of a 2 weight % solution of poly(vinyl benzyl thiosulfate sodiumsalt-co-methyl methacrylate-co-acrylicacid-co-N-butyl-N′-[2-(ethoxy-2-acrylate)ethyl]-1,4,5,8-naphthalenetetracarboxylicdiimide) (prepared in Thiosulfate Polymer 5) in water, 1 ml oftetrahydrofuran was added and the solution was then spin-coated onto aglass plate support at 1000 rpm. The resulting thiosulfate polymercoating was protected from UV and blue light at all times, and dried for5 minutes on a hot plate at 50° C. Absorption spectra of the thiosulfatepolymer coating were recorded before and after exposure to light. Afterexposure to light, the characteristic absorption spectrum ofnaphthalenediimide radical anion (compared with a chemically generatedauthentic spectrum) was observed. Formation of naphthalene diimideradical anion was concomitant with photo-crosslinking as evidenced by achange in solubility of the coating.

These results show that the thiosulfate polymer composition wasphotocrosslinked by photoinduced electron transfer to an electronacceptor.

USE EXAMPLE 3 Photopatterning Thiosulfate Polymer Composition Coating

To 1 ml of a 2 weight % solution of poly(vinyl benzyl thiosulfate sodiumsalt-co-methyl methacrylate-co-acrylicacid-co-N-butyl-N′-[2-(ethoxy-2-acrylate)ethyl]-1,4,5,8-naphthalenetetracarboxylicdiimide) (prepared as described above in Inventive Example 4) in water,1 ml of tetrahydrofuran was added and the thiosulfate polymercomposition was spin-coated onto a glass plate substrate at 1000 rpm.The thiosulfate polymer coating was protected from UV and blue light atall times, and was then dried for 5 minutes on a hot plate at 50° C. Thedried thiosulfate polymer composition coating was exposed to light usinga Hg lamp through a mask for 6 seconds and then washed with water,followed by washing with acetone. The exposed areas of the thiosulfatepolymer composition coating on the glass plate substrate were renderedinsoluble forming an image of the mask, whereas thiosulfate polymercomposition in the unexposed areas of the dried thiosulfate polymercoating was washed away.

These results show that the thiosulfate polymer compositions can be usedto prepare a photoresist useful for forming an image.

USE EXAMPLE 4 Selective Area Deposition of a Metal on PhotopatternedThiosulfate Polymer Composition

To 1 ml of an 11 weight % solution of poly(2-hydroxy-2-thiosulfatesodium salt ethyl methacrylate-co-methyl methacrylate) (prepared inSynthesis 4) in water, 2.2 mg of triphenylpyrrylium tetrafluoroboratesalt of electron-accepting photosensitizer component PS-21, 370 mg oftetrabutylammonium chloride, and 1 ml of tetrahydrofuran were added andthe solution was spin-coated on a glass plate substrate at 1000 rpm. Thethiosulfate polymer coating was protected from UV and blue light at alltimes, and then dried for 5 minutes on a hot plate at 50° C. The driedthiosulfate polymer coating was exposed to light using a Hg lamp througha mask for 10 seconds and then washed with water, followed by washingwith acetone. The exposed areas of the thiosulfate polymer compositioncoating on the glass plate substrate were rendered insoluble forming animage of the mask, whereas the thiosulfate polymer composition coatingin the unexposed areas was washed away.

This patterned coating was covered with an aqueous solution of silvernitrate followed by an aqueous solution of ascorbic acid, and washing.Metallic silver was deposited on the photopatterned areas.

These results demonstrate that the thiosulfate polymer compositions canbe used to form a photoresist that can be used to form an image usefulfor selective deposition of silver metal.

USE EXAMPLE 5 Selective Area Deposition of Metal Nanowires onThiosulfate Polymer Composition

Silver nanowires were prepared using a standard polyol procedure asdescribed in US Patent Application Publication 2011/0174190 (Sepa etal.), the disclosure of which is incorporated herein by reference.

Following three solutions were prepared:

Solution 1: A mixture of 6 grams of silver nitrate and 37 grams ofpropylene glycol in a beaker was stirred in the dark for about 6 hours.One half of Solution 1 was used for the initial and main additions. Theother half of the solution was kept in the dark to be used for the finalslow addition of silver nitrate during the second day of the reaction.

Solution 2: A mixture of 1.18 grams of tetrabutylammonium chloride wasdissolved in 10.62 grams of propylene glycol.

Solution 3: In a 1 liter, three-neck flask, a mixture of 7.2 grams ofpoly(vinyl pyrrolidone) and 445 grams of propylene glycol was heated toabout 90° C. Once the solution had stabilized at 90° C., it was purgedwith argon for 5 minutes. Then, 0.6% of Solution 1 was added into thereaction vessel and stirred for 10 seconds, followed by the addition ofSolution 2. After 4 minutes of allowing the seed reaction to begin,49.4% of Solution 1 was added to the reaction over the course of 45seconds, and the reaction was maintained at about 90° C. for 15 hours.All of these steps were carried out in vessels that were wrapped withaluminum foil to prevent exposure to light. After 15 hours of heating,the remaining 50% of Solution 1 was added slowly over the course of 4hours using a syringe pump. The reaction was allowed to continue for anadditional hour at which point heating was stopped and 100 ml ofdeionized water were added.

The whole crude reaction solution was allowed to settle for about 4days. The supernatant was silvery in color with a slight yellow tingeindicating a high concentration of Ag nanowires. The sediment wassilvery without a yellow tinge. The sediment was re-suspended indeionized water and viewed at 100× magnification using an oil immersionlens optical microscope. The resulting images showed a large populationof silver nanowires with some nanoparticles. The solution was then takenthrough a second settling process.

A thiosulfate polymer composition patterned coating was prepared in thefollowing manner:

An 8 weight % solution of poly(vinyl benzyl thiosulfate sodiumsalt-co-methyl methacrylate-co-1,8-naphthalimidohexyl acrylate)(prepared in Thiosulfate Polymer 4) in water was spin-coated on apolyethylene terephthalate substrate at 1000 rpm. The coating wasprotected from UV and blue light at all times, and then dried for 5minutes on a hot plate at 50° C., followed by exposure to light usingthe Hg lamp through a mask for 10 seconds, and the washed with water.The exposed areas of the dry thiosulfate polymer composition coating onthe glass plate substrate were rendered insoluble forming an image ofthe mask, whereas thiosulfate polymer composition coating in theunexposed areas was washed away.

The patterned thiosulfate polymer composition coating was immersed in a1 weight % solution of the silver nanowires in water for 1 minute andthen thoroughly washed with water. High resolution images of thepatterned composition coating clearly showed selective absorption ofsilver nanowires only in the photopatterned areas.

These results demonstrate that the thiosulfate polymer compositions canbe used to form photoresists that can then be used to provide an imagefor selective deposition of silver nanowires.

USE EXAMPLE 6 Formation of Conductive Patterned Coating UsingThiosulfate Polymer Composition Patterned Silver Wires

A silver metalizing bath was made by combining two separate baths. Onebath was a silver ion solution, while the other bath was a reducingagent solution. These two baths are denoted below them as Solutions Aand B, respectively.

Solution A:

Silver nitrate (0.817 g) was dissolved in 0.64 ml of ammonium hydroxideand then diluted by addition of 10 ml distilled water.

Rochelle's Salt Solution B:

Sodium potassium tartrate (Rochelle's salt, 2.86 g) and 0.205 grams ofmagnesium sulfate were dissolved in 10 ml of distilled water.

Plating Method:

Samples were immersed in a mixture of Solution A and B for 1 to 5minutes and subsequently washed with water.

Plating of Patterned Silver Nanowires:

The patterned coating of Use Example 4 was immersed in a silver platingsolution for 2 minutes and then washed with water. Metallic silverpattern was formed. Surface resistivity of the patterned coating wasmeasured to 10-15 Ω/□ using a four-point probe.

USE EXAMPLE 7 Imaging Thiosulfate Polymer Composition Coating

To 1 ml of an 8 weight % solution of poly(vinyl benzyl thiosulfatesodium salt-co-methyl methacrylate) (prepared as described inSynthesis 1) in water, various amounts in 1.6 mg of 4-phenyl-N-ethoxypyridinium hexafluorophosphate of electron-accepting photosensitizercomponent PS-12, various amounts in grams of tetrabutylammoniumchloride, and 1 ml of tetrahydrofuran was added and the resultingthiosulfate polymer composition was spin-coated on a glass platesubstrate at 1000 rpm. The coated thiosulfate polymer composition wasprotected from UV and blue light at all times. The thiosulfate polymercomposition coating was dried for 5 minutes on a hot plate at 50° C. Theresulting article was exposed to light using a mercury lamp through amask for 10 seconds and then washed with water, followed by washing withacetone. The exposed regions of the thiosulfate polymer compositioncoating on glass plate were rendered insoluble, forming an image of themask, whereas thiosulfate polymer composition in the non-exposed regionsof the thiosulfate polymer composition coating was washed away.

The results from these experiments demonstrate that the thiosulfatepolymer compositions can be used to provide articles that can be used toprovide photoresists.

USE EXAMPLE 8 Imaging Thiosulfate Polymer Containing Photosensitizer

To 1 ml of a 2 weight % solution of poly(vinyl benzyl thiosulfate sodiumsalt-co-methyl methacrylate-co-acrylicacid-co-N-butyl-N′-[2-(ethoxy-2-acrylate)ethyl]-1,4,5,8-naphthalenetetracarboxylicdiimide.) (prepared in Inventive Example 2) in water, was added 1 ml oftetrahydrofuran. The resulting thiosulfate polymer composition wasspin-coated onto a glass plate substrate at 100 rpm. The thiosulfatepolymer composition coating was protected from UV and blue light at alltimes. The thiosulfate polymer composition coating was dried for 5minutes on a hot plate at 50° C. The thiosulfate polymer compositioncoating was exposed to light using a mercury lamp through a mask for 6seconds and was then washed with water, followed by washing withacetone. The exposed regions of the dry thiosulfate polymer compositioncoating on glass plate substrate were rendered insoluble forming animage of the mask, whereas the dry thiosulfate polymer composition innon-exposed regions was washed away.

These results demonstrate that the thiosulfate polymer composition canbe used to form an article that can be imaged to form a photoresist.

USE EXAMPLE 9 Selective Area Deposition of Silver Metal on ImagedThiosulfate Polymer Composition

To 1 ml of an 8 weight % solution of poly(vinyl benzyl thiosulfatesodium salt-co-methyl methacrylate) (prepared as described above inSynthesis 1) in water, were added 1.6 mg of 4-phenyl-N-ethoxy pyridiniumhexafluorophosphate of electron-accepting photosensitizer componentPS-12, 250 mg of tetrabutylammonium chloride, and 1 ml oftetrahydrofuran. The resulting composition was then spin-coated onto aglass plate substrate at 1000 rpm. The composition coating was protectedfrom UV and blue light at all times. The thiosulfate polymer compositioncoating was dried for 5 minutes on a hot plate at 50° C. The driedthiosulfate polymer composition coating was then exposed to light usinga mercury lamp through a mask for 10 seconds and was then washed withwater, followed by washing with acetone. The exposed regions of the drythiosulfate polymer composition coating on the glass plate substratewere rendered insoluble, forming an image, whereas the thiosulfatepolymer composition in the non-exposed regions was washed away.

The resulting pattern in the thiosulfate polymer composition layer wascovered with an aqueous solution of silver nitrate followed by anaqueous solution of ascorbic acid, followed by washing. Metallic silverwas deposited on the patterned regions of the thiosulfate polymercomposition.

This example demonstrates that the thiosulfate polymer compositions canbe used to form articles that can be used to provide a photoresist thatcan be used for selective deposition of silver metal.

USE EXAMPLE 10 Surface Energy Modulation Using Thiosulfate PolymerComposition

To 1 ml of a 10 weight % solution of poly(vinyl benzyl thiosulfatesodium salt-co-methyl methacrylate) (prepared as described above inSynthesis 1) in water, 2.2 mg of electron-accepting photosensitizercomponent PS-22, 100 mg of tetrabutylammonium chloride, and 1 ml oftetrahydrofuran were added and the resulting solution was spin-coatedonto a glass plate substrate at 1000 rpm and then dried for 5 minutes ona hot plate at 50° C. The thiosulfate polymer composition coating wasprotected from UV and blue light at all times. The dried thiosulfatepolymer composition coating was then exposed to light using a mercurylamp for 100 seconds and then quickly rinsed with water and dried. Theexposed regions of the dry thiosulfate polymer composition coating onthe glass plate substrate were rendered insoluble from crosslinking ofthe thiosulfate polymer.

The water contact angle was measured before (45°) and after irradiation(65°) using the KRUSS contact angle measurement system. This exampledemonstrates that the thiosulfate polymer compositions can be used forphotochemical variation of surface energy of a coating or substrate.

The invention has been described in detail with particular reference tocertain preferred embodiments thereof, but it will be understood thatvariations and modifications can be effected within the spirit and scopeof the invention.

The invention claimed is:
 1. A method comprising: providing a polymericlayer comprising a non-crosslinked thiosulfate polymer that alsocomprises pendant organic charged groups, photochemically reacting thenon-crosslinked thiosulfate polymer to provide polymer layer areascomprising a crosslinked polymer having disulfide groups in thepolymeric layer, optionally washing the polymeric layer to remove anynon-crosslinked thiosulfate polymer while leaving the crosslinkedpolymer having disulfide groups in the polymeric layer, and contactingthe polymeric layer with a dispersion of metal nanoparticles to complexthe metal nanoparticles with the crosslinked polymer having disulfidegroups.
 2. The method of claim 1, comprising contacting the polymericlayer with a dispersion of gold, silver, platinum, palladium, or coppernanoparticles.
 3. The method of claim 1, comprising photochemicallyreacting the non-crosslinked thiosulfate polymer to provide polymerlayer areas in a predetermined pattern that comprise a crosslinkedpolymer having disulfide groups.
 4. The method of claim 1, wherein thepolymeric layer further comprises an electron-accepting photosensitizercomponent.
 5. The method of claim 1, wherein washing the polymeric layerto remove the non-crosslinked thiosulfate polymer is carried out usingan aqueous solution.
 6. The method of claim 1, wherein the polymericlayer further comprises an electron-accepting photosensitizer componentthat is a covalently-connected component of the non-crosslinkedthiosulfate polymer.
 7. The method of claim 1, wherein thenon-crosslinked thiosulfate polymer is a copolymer comprising, in randomorder: (a) recurring units comprising thiosulfate groups, and (b)recurring units comprising an electron-accepting photosensitizercomponent.
 8. The method of claim 7, wherein the copolymer comprises, inrandom order, (c) recurring units other than the (a) and (b) recurringunits, which (c) recurring units comprise a pendant charged group, the(c) recurring units being present in an amount of at least 0.1 mol %,based on the total recurring units in the copolymer.
 9. The method ofclaim 8, wherein the (c) recurring units comprise a pendant carboxy,carboxylate, phospho, phosphonate, phosphate, sulfo, sulfonate, orsulfite group.
 10. The method of claim 7, wherein the (c) recurringunits are present in an amount of at least 0.1 mol % and up to andincluding 50 mol %, based on the total recurring units in the copolymer.11. The method of claim 7, wherein the (c) recurring units are presentin the copolymer in an amount of up to and including 50 mol %, the (a)recurring units are present in the copolymer in an amount of at least 1mol %, and the copolymer further comprises (d) recurring units that havea total neutral charge and are present in an amount of at least 1 mol %and up to and including 49 mol %, all based on the total recurring unitsin the copolymer.
 12. The method of claim 11, wherein the molar ratio ofthe (a) recurring units to the (d) recurring units in the copolymer isfrom 1:3 to 3:1.
 13. The method of claim 1, wherein the non-crosslinkedthiosulfate polymer comprises (a) recurring units comprising thiosulfategroups and (c) recurring units that comprise a pendant charged group inan amount of at least 0.1 mol %, based on the total recurring units inthe non-crosslinked thiosulfate polymer.
 14. The method of claim 1,wherein the polymeric layer further comprises an electron-acceptingphotosensitizer component in an amount of at least 0.1 mol % and up toand including 10 mol %, in relation to the molar amount of thiosulfategroups present in the polymeric layer.
 15. The method of claim 1,wherein the polymeric layer further comprises an electron-acceptingphotosensitizer component that is a compound separate from thenon-crosslinked thiosulfate polymer.
 16. The method of claim 1, whereinthe polymeric layer further comprises an electron-acceptingphotosensitizer component that is an organic photosensitizerN-containing heterocyclic compound.